2025 Theses Doctoral

Strategies for Optimized and Accessible Rehabilitation for Children with Cerebral Palsy: Integrating Neuromodulation, Motor Learning, and Recreational Participation to Enhance Function

Metelski, Nicole M.

Background.
Cerebral palsy, the most common cause of childhood physical disability, is a heterogeneous neurodevelopmental condition that causes impaired postural development, movement deficits, and activity limitations. Approximately one-third of children with cerebral palsy have unilateral spastic cerebral palsy (USCP), which primarily affects upper extremity sensorimotor function, coordination, and motor planning. Intensive upper extremity therapies can improve motor function in children with USCP, but their high dosage requirements limit feasibility in clinical practice. Adjunctive approaches that enhance the effectiveness and accessibility of rehabilitation may help bridge this translational gap.

Aim.
This dissertation examined adjunctive strategies to optimize and extend rehabilitation for children with cerebral palsy, particularly USCP, by integrating neuromodulation, motor learning, and recreational participation approaches. Across four studies, it investigated: (1) how non-invasive brain stimulation impacts upper extremity outcomes in USCP; (2) whether transcranial direct current stimulation (tDCS) modulates corticospinal excitability; (3) whether tDCS can improve motor learning; and (4) how recreational physical activities can support motor and psychosocial outcomes while extending practice opportunities beyond formal therapy.

Methods and Results.
The first study (Chapter II) systematically reviewed the effects of non-invasive brain stimulation, including repetitive transcranial magnetic stimulation and tDCS, on upper extremity outcomes in children with USCP. Evidence supported its safety and feasibility for this population, but its effects on upper extremity outcomes were equivocal. Studies suggest that efficacy may be related to heterogeneous participant characteristics and stimulation parameters.

Building on these findings, the second study (Chapter III) was a mechanistic study that applied a single session of anodal tDCS (20 minutes, 2 mA) to the primary motor cortex in children with USCP and modeled transcranial magnetic stimulation-derived recruitment curves before and after tDCS. Logistic modeling provided a feasible method to estimate corticospinal excitability. Group-level changes in recruitment curve metrics were not significant, but individual responses were highly variable, with a subset of responders showing increased excitability after tDCS. This study highlighted the importance of physiology-informed, individualized tDCS interventions.

The third study (Chapter IV) was a randomized pilot study that examined whether anodal or cathodal tDCS can enhance bimanual motor skill learning during a novel task compared to sham stimulation, and how kinematic parameters changed with learning. All groups demonstrated motor learning over the intervention period, regardless of stimulation type. Active tDCS did not alter the magnitude of performance improvements, but was associated with earlier within-group learning plateaus than those who received sham stimulation in this small sample.

The final study in this dissertation (Chapter V) systematically reviewed recreational physical activity interventions for children with cerebral palsy, identifying leisure- and sport-based participation contexts that promote motor and psychosocial outcomes while extending opportunities for practice beyond therapy. Recreational physical activities were generally associated with task-specific improvements and psychosocial benefits, though evidence was limited by small sample sizes and heterogeneous study characteristics. These activities offer feasible participation-based contexts to extend practice and engagement beyond structured therapy.

Conclusion.
Together, these studies advance understanding of how neuromodulation and low-cost, activity-based strategies may be combined to improve the dose-efficiency and accessibility of upper extremity rehabilitation for children with cerebral palsy. By integrating mechanistic, behavioral, and participation-level perspectives, this dissertation advances the research on scalable, evidence-based strategies to enhance motor function and participation for children with cerebral palsy.